Preparation and modification of magnesium oxide and insulation properties

　　Magnesium oxide is a wide bandgap insulation material, and its excellent dielectric, adsorption and other characteristics have made it widely concerned in the application of improving the insulation performance of electrical materials such as low-density polyethylene LDPE and cross-linked polyethylene XLPE. It is of great significance to conduct systematic research on the insulating properties of magnesium oxide.

　　Hebei Xintao New Material Technology Co., Ltd. prepared the process and conditions of magnesium oxide with good insulation performance, analyzed the influence of the physical properties of magnesium oxide on its insulation properties, and determined the process conditions for the preparation of magnesium oxide with excellent insulation properties. On this basis, the process technology route for preparing high insulating EP/magnesium oxide composite materials was developed based on the natural raw materials of Inner Mongolia Kaxiong Naurmanite salt and white sodium magnesium alum symbiotic ore and kelantai salt lake brine, combined with the research results of predecessors.

　　The main research contents and conclusions of Hebei Xintao New Material Technology Co., Ltd. are as follows:

　　1. First of all, the pure reagents are analyzed by direct precipitation method to prepare magnesium oxide, and the influence of operating conditions on the insulation properties of magnesium oxide is explored, such as reaction temperature, reaction time, ammonia solution concentration, dispersant type and dispersant addition. XRD, particle size distribution characterization and volume resistivity were determined for the resulting magnesium oxide. The results show that the insulation performance of magnesium oxide is independent of its crystallinity and its particle size distribution. The narrower the particle size distribution and the smaller the particle size, the better the powder insulation properties.

　　2. In order to obtain magnesium oxide with narrow particle size distribution, on the basis of the experimental results of the direct precipitation method, the preparation of magnesium oxide by uniform precipitation method is explored to improve the particle size distribution and particle size of the powder. The effects of calcination temperature and calcination time on the insulating properties of magnesium oxide were discussed. The results show that the uniform precipitation method effectively reduces the particle size distribution width of magnesium oxide. By analyzing the PL pattern and the measurement results of volume resistivity, it is concluded that the insulation performance of magnesium oxide is independent of the internal Schottky defect level of magnesium oxide crystals.

　　3. In order to improve the dispersibility of magnesium oxide in the organic phase, the influence of pure surfactant on the wet modification of the obtained magnesium oxide was analyzed, and the influence of modifier type, modification temperature, modification time and modifier addition amount on the volume resistivity of the product was discussed. The results show that modification can significantly improve the insulation performance of the product; With the improvement of the modified temperature, the modification time and the amount of modifier, the resistivity of magnesium oxide shows a trend of first increasing and then decreasing, among which the insulation performance of magnesium oxide modified with sodium stearate is better, and the volume resistivity reaches 17711MΩ・m. By analyzing the FT-IR pattern and the volume resistivity measurement results, it is believed that the improvement of sodium stearate on the insulation performance of magnesium oxide is mainly due to its strong adsorption effect on magnesium oxide.

　　4. Using Kaxiong Naur manganese salt and white sodium magnesium alum symbiotic ore and Kelantai salt lake brine as the magnesium source, EP/magnesium oxide composite materials are prepared according to the suitable preparation and modification process obtained in the previous period. EP/magnesium oxide was characterized by bending properties and volume resistivity. Experimental results show that combined with the research results of predecessors, the nano-magnesium oxide with good insulation properties is prepared using natural materials as raw materials. High insulating nano magnesium oxide filler can effectively improve the insulating properties of EP.